yashsingh1/xdaforums huggingface dataset:
[Nexus 7 (2013) Q&A] CornellEngineer:
Bricked Nexus 7 2013 LTE

Hey k23m,

First I wanted to thank you for your excellent thread...it really helped me to troubleshoot a recent Nexus 7 failure.

We have 3 Nexus 7s...two of them are 2013 Wifis that we bought new. The third one was an unlocked Nexus 7 2013 LTE that I bought used off eBay in mid-2015. It worked great...right up until a few days ago when my partner brought it to me locked up on the Google boot logo. Be advised that since we got it I never updated the OS...I think it was running 4.2.2 the entire time but I can't be sure about that.

Per your instructions I hooked it up to my PC and ran your "fastboot oem gpt-info" command...sure enough it reported back "partition[30].size 27852783 KB" which you said indicates that it has the high-failure rate Kingston eMMC. Next I ran the "fastboot format cache" command and it got hung up trying to erase the cache which apparently is a sure sign the flash chip is shot.

I pulled the motherboard out last night...unlike the Wifi model the Nexus 7 2013 LTE version has shields over all the chips on both sides of the MB. I pried the 2 shields off the same side of the mobo shown in your original post assuming that the eMMC chip for the LTE version would be on the same side as you showed for the Wifi one but I couldn't spot any chips that look like they're the flash memory so it must be on the other side of the board. If I get around to taking the shields off the back side to visually verify which flash chip is on this particular unit I'll let you know what brand the eMMC is so you can add it to your database. If you are at all familiar with the LTE model maybe you can verify that the eMMC chip is indeed on the opposite side of the MB compared to the Wifi model? I did spot 3 identical large Hynix chips on the now-exposed front side but I believe those are SDRAM.

Since I'm pretty sure it's a flash failure based on the info you provided I ordered a replacement LTE MB. It was under 30 bucks and I am just real curious to see if I can fix it so I gambled a few bucks. I may have a few more questions for you later if I can get it to boot up...but it's coming from China and may not get here until mid-March.

Anyways, thanks again for this thread...it really helped a lot. I haven't read through every single page but I hadn't seen any posts about the 2013 LTE model so I just thought I'd mention that the flash memory fails on these ones too...which shouldn't be all that surprising if they utilize the same failure-prone chips.

Regards,

Dale
[Nexus 7 (2013) Q&A] k23m:
Hello CornellEngineer, thanks for your report and observations. I have 3 N7s but all are WiFi models and I have never inspected an LTE personally. You are right, the eMMC chip is on the top side - see attachment. It will be a Kingston for sure, it's data partition size is unique unless repartitioned. When you get a mobo replacement, update it with the latest stock or a new custom ROM.

Cheers :highfive:
[Nexus 7 (2013) Q&A] k23m:
I follow this philosophy too but infrequently I do upgrade to major, stable OS releases.You have inspired me to compare KitKat to modern alternatives using CF-Bench v1.3 benchmark app:

Full Benchmark Score - Native/Java/Overall

LineageOS 17.0 (Android 10) = 31369/17761/23204

LineageOS 14.1 (Android 7.1.2) = 25320/12060/17364

MOB30X (Android 6.0.1) = 25554/19947/22189

KTU84P (Android 4.4.4) = 25580/7857/14946​

As you can see KitKat has no advantage whatsoever. Except for testing and development, I am not yet on LOS17 and still use the really stable LOS14.1 - the last official version is here and new, unofficial, highly recommended releases with security updates are here. The last official MOB30X (Android 6.0.1) actually has relatively good performance and seems optimal for your usage - Restock can do the update easily.

Cheers :good:
[Nexus 7 (2013) Q&A] hix3r:
Diagnostics

Hi, I seem to have issues with my Nexus 7 2013 LTE (deb). It was purchased in 2014 at a store as new, nobody owned it before.

In 2018 it seemed the battery started having problems, it drained quickly from full, the tablet would randomly restart sometimes during the day even if it wasn't used and on a charger, you could see the display light up and the tablet reboot multiple times a day even tough nobody was even near it.

This finally resulted in the tablet going dark. not responding to button presses even with it on a charger.

I figured the battery was dead and messing with something, so I ordered a decent battery replacement, took apart the device and found the original factory battery swollen, puffed up like a baloon inside. As it puffed up it pulled out the ribbon cables above it from their sockets. Changed the battery, plugged the cables back. Tablet was still working, yay. Formatted everything, set up some custom ROMs etc. Seemed fine.

Except the random reboots still persisted, I formatted, wiped, tried original, custom ROMs, kernels etc. the tablet would still reboot at random times during the day, sometimes during use, sometimes not. Fast forward to today, it rebooted again as usual out of the blue, but now it is stuck in a boot loop. It gets through the "Google" logo part and starts to load LineageOS (the LineageOS boot animation is playing) but it freezes midway and reboots. I can get to fastboot and TWRP but TWRP shows errors mounting partitions.

Found this topic, looked around, ran the diagnostic batch file, you can find the twrp.txt output it produced on pastebin at pastebin DOT com SLASH V9r4tq9e (There were some errors, like "mounting /system on ext4 failed: No such file or directory") Can't attach the file and can't post any outside links unfortunately since I am apparently under the 10 post limit.

Also looked at the eMMC on the board, it is a Hynix chip.

SK hynix
H26M64003DQR
e-NAND 323A
M12J3757AQ

The main board is ME571KL_MB rev. 1.7

So now I am asking for some diagnostic help, is my eMMC chip gone? There weren't any "critical data" on the device I saved off everything already when I changed the battery and didn't store anything important on it. (except low level stuff like IMEI or MAC address... partitions etc.)

Thank you.
[Nexus 7 (2013) Q&A] k23m:
!

Thank you for the logs and a very comprehensive report, I wish all users would be so thorough!

Firstly, your eMMC is definitely OK, but clearly there is a hardware problem somewhere.

Secondly, let's "Restock" your tablet before hardware tests.

When the stock ROM is up and running, please do:

- run something like CPU Throttling Test (change the "end test" setting to a few hours) to stress-test your N7

- use a hairdryer on it to further increase its operating temperature

The objective is to check if the reboots happen during heavy usage. If it consistently reboots while hot, check if un/re/plugging the charger makes a difference.
[Nexus 7 (2013) Q&A] k23m:
Very interesting observation, and it increasingly looks like a power or power communication (I2C) issue, note your TWRP log:

<3>[ 2.038391] qup_i2c qup_i2c.0: QUP: I2C status flags :0x11100c8, irq:226
<3>[ 2.038635] qup_i2c qup_i2c.0: I2C slave addr:0x55 not connected
<3>[ 2.038787] bq27541-battery 0-0055: bq27541_get_psp: i2c read for 9 failed
<3>[ 2.038970] power_supply battery: driver failed to report `charge_now' property: 4294967274

These are unique errors which I have never seen before. The `charge_now' property occasionally can't be read from the battery gauge IC via I2C. As you have tried 2 or 3 batteries already, it seems to be a mobo problem. Please check the data lines from the battery plug, look for cracks or signs of corrosion.

In this context it may be a long shot but try to test it out (waiting for reboots) with a charger constantly on. If the cable is too inconvenient, use a power bank for better portability.

With intermittent faults, component swaps can help in troubleshooting and diagnosis. As it appears to be a mobo problem, getting a new one may be necessary. A few days ago XDA user "ordered a replacement LTE MB. It was under 30 bucks ...but it's coming from China and may not get here until mid-March." Is it an option?
[Nexus 7 (2013) Q&A] hix3r:
Wait and see

Thank you for the help. I thought the battery handling ICs are usually inside the batteries themselves so that could mean it is just incompatibility with this OEM battery replacement or the chip inside the battery is partially faulty?

The tablet was running 24/7 with the charger connected before, only used it near the bed so didn't feel the need to disconnect it, in fact very rarely did I disconnect it.

Well, I could replace the board, but something on the charging board could be faulty, which damaged something on the main board... With the amount I spent on the batteries (bought a new charger as well) plus the price of the main board I would be halfway to the price of a new tablet like a Mi Pad 4 (which would be much more powerful as well). Not sure it would be worth it to keep tinkering with this in the long run.

To be honest I could tolerate the reboots since they rarely happen during use. If possible I would like to avoid it destroying the installed system, not sure how a reboot messed up the files on the eMMC so much it resulted in a boot loop?

I think I will try to use it for now and observe if any reboots happen with a Restocked vanilla system, Thank you for that!
[Nexus 7 (2013) Q&A] aungmyoswe:
1322 photo here...

i dont know what you mean .., sorry
[Nexus 7 (2013) Q&A] k23m:
Thank you again!

Did you flash a new ROM just before the failure or it happened during normal tablet usage?
[Nexus 7 (2013) Q&A] aungmyoswe:
actually, it not mine. from my friend.he ask me for help, that why.

he said., he make the OTA update in night and go to sleep without finish the update ,in the morning the tablet is dead. i dont know why but the tablet is really dead:D:D

thank for reading...:o
[Nexus 7 (2013) Q&A] k23m:
Can you try this method to enter the 9006 mode?

:fingers-crossed:
[Nexus 7 (2013) Q&A] graphdarnell:
Don't shoot the messenger, but on mine, the one with Kingston that failed bears the date code 1322 (sticker 51.1.13), which was probably mfg'd in mid- '13, whereas the one still running has the sticker 51.1.5 (apparently made prior), which I don't have access to right now. I gave it to a friend to sell on Ebay. The guy who bought misdiagnosed his problem as motherboard-related, and now seeks to return it. I will update once I get a hold of it again.
[Nexus 7 (2013) Q&A] k23m:
Thanks so much graphdarnell. We know now all details of the 3 Kingston bricks:

1x 51.1.5 - 1244
2x 51.1.13 - 1322

Not enough stats yet but I'd too get rid of Kingston :highfive:
[Nexus 7 (2013) Q&A] aungmyoswe:
Thanks you all guy.......

But i want to know about that table to fix. How to do? . Is there a way? .Only RIFF box can fix ?. If there is a way to fix it, i need step by step guide.:D:D

my english is week so i dont understand too much:confused::confused::confused::confused::confused:

how to fix that tablet?
[Nexus 7 (2013) Q&A] k23m:
RIFF box can reflash only a good eMMC. We'll try to test your eMMC to see if it is still writeable. As there is currently no solution for the Qualcomm 9008 mode (on Nexus 7) try the 9006 method I mentioned before.

Btw when you plug it in to a charger or PC, does a LED blink for 15 seconds?
[Nexus 7 (2013) Q&A] aungmyoswe:
No bro, there is no LED light when connected to pc. nothing happen on tablet.
[Nexus 7 (2013) Q&A] graphdarnell:
For the sake of clear conscience, I didn't try to dump the Kingston motherboard out of fear. The reason is simple: despite the article's seemingly fixation on it :D:D:D, I've yet to see convincing evidence that Kingston is more prone to failure than any other brand you might find in the Nexus 7.

The people who wrote the article are entitled to their opinion, but it's just that - their opinion uncorroborated by data. The fact of the matter is most people bricked their tab while trying to upgrade to Lollipop or Marshmallow via official OTA. I've never bricked one using AOSP-based custom roms; and for a while now I've had a 32GB Kingston that still runs without issue.

I'm aware of NO report of significant number of Kingston tabs bricked when put to regular uses. At least no more than those equipped with Hynix or Toshiba. Which indicates hardware is stable, regardless of eMMCs' brand.

Hence, I have all the reasons to believe it's the OTAs instead that caused the problem, which occurred with the Asus TF line as well at least 4 years running now. Thus, there's no reason to surmise or panic should you happen to own a Kingston because unless there's more concrete proof, the statement that Kingston "oftenly" fail stems not from fact.
[Nexus 7 (2013) Q&A] k23m:
What statement would you accept as a fact? A well spelled one maybe?

Look at the date of their article - May 2015 - the same month as the beginning of our effort. They already had a solution for OTA/whatever bricking while we're still scratching our heads.

Ain't it a fact convincing enough for you?
[Nexus 7 (2013) Q&A] graphdarnell:
Let's keep this level-headed. I'm for a fix that would benefit all. If I turn out to be completely wrong eventually, I'm ok with that, so long as we do not get distracted along the way in the interest of time.

When you say they had a solution, what is it? The statement about replacing the eMMc is

(1) preposterous because everybody already knows that. One might as well tell people to go buy a new tablet – and those who did wouldn't be here discussing anything. Secundo, it doesn't confirm Hynix or Toshiba do not fail. Tertio, it certainly doesn't say when they do, they don't have to be replaced. If they do, how does it convey the other brands are different from or better than Kingston under the same conditions?

(2) irrelevant because it doesn't inform you (a) what caused the brick and how; (b) under what circumstances; and (c) how to fix it short of (1) above. For our purpose, it's of little or no help simply because it contains nothing we haven't already known, and that in itself is not enough to advance our effort.

That's why we're still scratching our heads. But let's keep scratching until the itch is gone.:D:D:D
[Nexus 7 (2013) Q&A] k23m:
Back to this pile of digital rubbish...

JTAG of course. Not sure if you are so clueless or just a plain troll - my guess is 60/40.

"preposterous" - what a buffoon, replacing BGA (eMMC) chip is a 4-minute job.

Let go of these nauseating tirades mate, do some gardening instead, it's the best use of your retirement time.
[Nexus 7 (2013) Q&A] k23m:
Please upload your bricked device's memory dump for investigation.

- download New Qualcomm 2012.rar

- extract the "fre" folder

- connect your N7 to PC and when asked for a driver point it to the above folder

- download New_Qualcomm_QPST-2.7.422.zip

- extract it and run "setup.exe"

- run Start/QPST/MemoryDebugApp.exe

- in Memory Debug keep clicking "Browse" until you see a new COM port

- in Memory Debug click "Get Regions"

- in Memory Debug select and save "CODERAM.BIN"

- upload "CODERAM.BIN" here

Thank you in advance.

:highfive:
[Nexus 7 (2013) Q&A] k23m:
UPDATE

New uploads to my N7 collection:

Asus_Nexus_7.rar

Asus_Nexus_7.txt

nexus7 jtag maybe.jpg

RIFF Box JTAG GettingStarted.pdf

RIFF Box JTAG Manager Setup v1.56.exe

I intend to do peek into this encrypted RIFF JTAG "Asus_Nexus_7" - stay tuned.

:good:
[Nexus 7 (2013) Q&A] graphdarnell:
Given that the continuity of those points between the MB and daughter card is direct, would a stand-alone female micro-usb jack achieve the same purpose? I don't have any problems doing it with the daughter card, but just wonder aloud before taking the plunge.
[Nexus 7 (2013) Q&A] k23m:
Yes it would but MB-DB connection is more robust for sure, and if we succeed in unbricking it, you could put the back cover on and actually use it again (no touch control of course - but with OTG or BT instead).

Either way, select the thinnest multi-strand, quality copper wires for this application or else you will rip out the tiny connection pads. For GND use a thicker wire.

I hope your soldering iron is temperature controlled - do not exceed 350C for this task.

:fingers-crossed:
[Nexus 7 (2013) Q&A] C5Longhorn:
I just received my tablet back from ASUS. I assume they issued me a new one or a refurb. I checked the new tablet using SD Insight and got the following details:

Hynix

HBG4e

31 GB

Jun 2013
[Nexus 7 (2013) Q&A] k23m:
Thank you, I updated our stats - the first ASUS-repaired report!

Is it a definitely different unit with new serial number?

Did they flash the latest Android?
[Nexus 7 (2013) Q&A] k23m:
No worries. Don't give up on this great tablet :fingers-crossed:

Regarding the battery handling IC, there is no incompatibility, your log shows that it works fine most of the time...

<5>[ 1.783966] bq27541_get_psp voltage_now= 4298000 uV
<5>[ 1.785186] bq27541_get_capacity = 100% ret= 100
<5>[ 1.786376] bq27541_get_psp temperature= 257 (0.1?XC)
<5>[ 1.787689] bq27541_get_psp current_now = -44 mA
<5>[ 1.788909] bq27541_get_psp charge_now (compensated) = 3823000 uAh
<5>[ 1.790252] bq27541_get_psp charge_avg (uncompensated) = 3835000 uAh
<5>[ 1.791473] bq27541_get_psp charge_full = 3823000 uAh
<5>[ 1.792785] bq27541_get_psp charge_design = 3850000 uAh
<5>[ 1.794006] bq27541_get_psp energy_now = 14145000 uWh
<5>[ 1.795318] bq27541_get_psp charge_counter = 0 uWh
<5>[ 1.796539] bq27541_get_psp power_now = 219000 uW
<5>[ 1.797851] bq27541_get_psp cycle count = 5

There is no separate charging board, all power/charge components are on the motherboard - see attachment and this ASUS Power doc. The daughterboard has only USB charge port but no active power components.

Cheers
[Nexus 7 (2013) Q&A] hix3r:
Thanks

The frustrating part is the CPU, RAM, eMMC, modem chips seem to work fine and these are the most "expensive" parts on the board... Seems such a waste to buy an entirely new board because some penny cost battery IC is acting up even if the replacement board is just around 30 bucks... Another concern would be that I can't really tell what eMMC chip would be on the new board, it could be one with a Kingston eMMC. The boards are either scavenged ones or they are remaining stock from the original manufacturing so both could have still working, but flaky Kingston chips on them...

Oh well, if the problems get super annoying I'll consider a new board.
[Nexus 7 (2013) Q&A] CornellEngineer:
Nexus 7 LTE Motherboard

While looking over k23m's excellent responses to my questions I saw your recent posts. If you find yourself wanting to buy a new mobo for your LTE this is where I ordered mine...

https://www.aliexpress.com/item/4000556014832.html

Not too crazy about AliExpress...their website is horrible and their tracking features are virtually useless. But I saw where you have previously bought something from them yourself so maybe you have no qualms about them. This is only the second thing I've ordered on this site so we'll see how it goes. My first order for a drone carrying case took forever to get here but it finally arrived recently and was as described and a nice case so hopefully I'll be lucky enough to go 2-for-2 on this site. Can't vouch for the board or the supplier since I might not receive it until mid-March but I'll try to make a short post whether it worked or not when the time comes in case anybody else ends up going this route.

---------- Post added at 09:43 PM ---------- Previous post was at 09:40 PM ----------

To k23m...

Wow, that was a terrific comparison you did there. Based on your benchmarks think I might try updating to Marshmallow on this broken Nexus 7 LTE model after I receive and install the new motherboard assuming it brings it back to life.

I'm always a little afraid of accidentally bricking these Android tablets by doing something wrong since I don't have all that much experience working on them like I do PCs. That's the reason I joined this forum in the first place a few years ago...I have a couple real nice Amazon Fire HD 8.9 tablets that I wanted to convert over to a more conventional Android device. I read a lot of how-to posts and asked a few questions and got close to trying it but then I chickened out and never did anything.

If I don't get to a certain comfort level using the RESTOCK tool you mentioned, can I simply keep updating the tablet over the internet one step at a time until I get to 6.0.1? Are there any disadvantages of doing it this crude way rather than using RESTOCK to go right to that version...other than it will take me several steps and will take a bit longer?
[Nexus 7 (2013) Q&A] k23m:
Thank you for the link. Hopefully it will not be another mobo with a Kingston eMMC. Check it with this app. If it is a Kingston, then flash it once and try to use it read-only mostly. They don't fail (often :)) if left undisturbed. Years ago people speculated that buggy OTA updates killed the tablets but it's the massive flash rewrite during any OS update that triggers the catastrophic failure of these badly manufactured chips - it is not a typical, gradual flash memory wear-out. With this in mind I do not recommend OTA/several steps as it can be dangerous. In any case, it is unnecessary, there is no relevant OTA advantage in this context, many years after product EOL. Well, OTA has the advantage of updating OS with locked bootloader, while Restock will automatically unlock it if it is locked and always erase all data in the process so do your backup first!

:highfive:
[Nexus 7 (2013) Q&A] CornellEngineer:
Success

I am happy to report that I just received the replacement LTE motherboard from China almost 3 weeks ahead of schedule and after spraying it with Lysol and dunking it in alcohol (just kidding!) I installed it into the Nexus 7 tablet and I'll be damned if that SOB didn't fire right up. It's running 4.4.2 and I think I'm gonna keep it right there for the time being and avoid flashing any newer versions since this version is plenty good enough for her to read her books. I'll check out which flash chip is on the board at some point just out of curiosity but beggars can't be choosers...I was lucky to find a reasonably priced replacement mobo that works at all halfway around the world so if it's a Kingston we'll just have to see how long it lasts.

Just gave it to her and she's real happy...she had been using an Amazon Fire HD 8.9 I provided her while waiting for me to repair her Nexus and while the Fire is a nice tablet it's pretty damn big and heavy to comfortably hold and read in bed.

So thanks once more for this thread...I'm not sure I woulda been able to fix this sucker if it had not been for your troubleshooting tips in your original post.

---------- Post added at 07:04 AM ---------- Previous post was at 06:07 AM ----------

If you're sure that everything else on your mobo is working and it's just a failed component in the charging circuit, instead of replacing the entire board why don't you consider picking up one of those inductive chargers?

https://www.androidcentral.com/new-nexus-7-wireless-charging-feature

I researched some a few years ago and ended up not getting one but pretty sure you can buy a decent one on Amazon or elsewhere for the same price or considerably less than a replacement motherboard while avoiding the hassle of tearing your tablet apart. Besides, the Nexus 7 was notorious for having very weak mini-USB ports and over time they distorted enough so that the connector often wouldn't make good contact and then didn't charge properly because the pins weren't making good contact. This can be repaired by taking the back of the Nexus and then squeezing the port's walls slightly to get a tight fit again but an inductive charger bypasses this flimsy port altogether.